This invention relates to a method for improving the strength of water-saturated soft soils.
It is generally known from past experience that a water-saturated soft soil deposited on the bottom of seashore, river, lake and lagoon must be strengthened to enable passage of people or traffic vehicles or conveyance of construction machines on reclaimed soft grounds formed by dredging such water-saturated soft soil. In one such method, a strengthening agent or solidifying agent comprising a cement, quick lime, water glass, asphalt or organic macromolecular substance is added to the soft soil. However, this method is not altogether satisfactory since these strengthening agents are poor in strength-improving effect or are economically unfeasible. Especially, in the case of the large-scale treatment of soft soil of a high water content, such as a certain kind of sludge or mud called "hedoro" deposited on the bottom of rivers or the seashore, the amount of soil to be treated in one batch may reach several thousand to several million cubic meters, thus requiring the addition of an extremely large amount of the strengthening agent, and hence the strengthening agent employed should be as cheap as possible and should be capable of significantly improving the sail strength even in smaller amounts.
In U.S. Pat. No. 4,299,516, there is disclosed a method in which a water-saturated soft soil is improved in its strength by incorporating thereinto an additive composed of gypsum and a mixture of Portland cement and a water-granulated iron blast furnace slag. Whilst this method may impart a desirable strength to the soft soil, it is not quite satisfactory from an economic or ecological point of view.